The major challenge facing Pfs25-based TBV development is to find a formulation with great safety profile and capable of inducing sustained high antibody responses. Previously the LMIV has demonstrated that conjugating Pfs25 with carrier protein ExoProtein A (EPA) of Psuedomonas aeruginosa greatly enhance the immunogenicity of the recombinant Pfs25 produced in Pichia pastoris. A process was developed to conjugate Pfs25 with rEPA, and cGMP-grade Pfs25-EPA conjugate was manufactured and formulated with Alhydrogel. A Phase 1 trial was conducted in US. After demonstrating that vaccine was safe, immunogenic, and could induce transmission reducing activity, LMIV began a Phase 1 trial in Mali, the first time in the world evaluating the vaccine safety, immunogenicity, and transmission blocking activity in target population.